1. Field of the Invention
The present invention relates to an optical receiver module and an optical module.
2. Description of the Related Art
In recent years, demands for optical modules for high speed communication have been increasing. An optical receiver module for a transmission speed of about 10 Gbps has a shape of a coaxial type package or a box type package. In the package, a light receiving element and an amplifier (such as a trans-impedance amplifier and an automatic gain control amplifier) are disposed close to each other, and electrode pads are connected to one another by wires. The package has a lens as well. When an optical signal is inputted through an optical fiber, the beam spot of the optical signal is stopped down through the lens, and the optical signal is converted into an electrical signal through photoelectric conversion in an absorber layer (an optical receiver unit) of the light receiving element. An electrical signal, which is usually very subtle as being of a few microamperes to a few milliamperes, is amplified by the amplifier before being outputted as a voltage signal.
The amplifier receives a supply of power from a power source outside the package, and a bias is applied to the light receiving element. A high speed optical receiver module adapted to a speed of 10 Gbps or faster is designed such that a power line runs through an electrode pad having a plate capacitor and a chip capacitor, for example, in the package in order to prevent noise generation and signal deterioration due to oscillation or other causes. The inside and outside of the package are electrically connected to each other by a lead pin on the package or a transmission line pattern or the like on the ceramic substrate.
Japanese Patent Laid-open Publication No. 2014-192510 discloses an optical receiver module in which a bias to a light receiving element passes through a wire from an amplifier, and a signal from the light receiving element is outputted through a wire to the amplifier. As these wires are aligned in parallel with each other, crosstalk due to electrostatic induction and electromagnetic induction deteriorates signal transmission characteristics in a high-speed operation. In particular, varying the voltage of a power source will cause noise, and signal quality is thereby deteriorated.